Final answer:
In an ER diagram, the relationship minimum indicates the least instances of one entity connected to another and is usually specified as a zero or one.
Step-by-step explanation:
A relationship minimum in an ER diagram is the least number of instances of one entity that relates to a single instance of another entity.
On an ER diagram, minima are usually specified as a zero or one.
For example, if an ER diagram is depicting the relationship between a library and books, the minimum might be set to one if each book is required to be in at least one library, or zero if a book can exist in the system before it is placed in any library.